Proximity sensors are sensor devices configured to detect presence of nearby objects without any physical contact. For example, proximity sensors are commonly used in electronic gear to turn power-consuming circuitry on or off in response to the proximity sensors detecting something nearby. Use of proximity sensors in such applications may be particularly efficient because they may provide for detecting proximity without having to make physical contact.
A proximity sensor comprises a transmitter and a receiver. An optical lens assembly is coupled to the emitter in order to collimate the radiation to specific directions or distances of interest so that the radiation can be fully utilized for high power efficiency. Similarly, an optical lens assembly may be coupled to the sensor to focus radiation from a specific direction on to the receiver.
The use of an optical lens assembly may increase power efficiency. However, a portion of radiation transmitted through the optical lens assembly, particularly at an outer periphery or the circumference area of the lens, may be lost. It may be desirable to redirect the otherwise lost radiation for other purposes.
Additionally, proximity sensors are usually used to detect an object at a predetermined but comparatively large distance. However, in some applications the proximity sensors may also be required to detect the presence of an object at a location very close to the proximity sensor. This may lead to competing design requirements for optical lenses for proximity sensors.
Proximity sensors may be formed as a single integrated device incorporating optical lens assemblies, an emitter die and a detector die inside a single body. Alternatively, proximity sensors may be assembled from pre-manufactured components. For example, proximity sensors may be assembled from packaged light-emitting devices and packaged detectors. In another example, pre-manufactured optical lens assemblies may be used, rather than being formed from raw material during the manufacturing process. Consequently, a feature of an optical lens assembly found in proximity sensors may be utilized in other optical devices having similar optical components targeted for other applications other than proximity sensing.